The present disclosure relates to an image processing apparatus, an image processing method, and a program causing a computer to execute the image processing method. Specifically, the present disclosure relates to an image processing apparatus and an image processing method with which the number of frames per unit time in a moving image is changed and to a program causing a computer to execute the image processing method.
In image processing apparatuses in related art such as television receivers, a frame rate conversion to change the number of frames per unit time, i.e., a frame rate, in a moving image is performed in some cases. For example, in order to smoothen the motion of an object in a moving image, a frame rate conversion to increase a frame rate, which is called an up-conversion, is performed.
In such an up-conversion, a frame interpolation method in which an interpolated frame is generated from original frames and inserted between the original frames is widely used. In the frame interpolation method, motion compensation processing to detect the motion of an object in the original frame and generate an interpolated frame based on the motion is performed. This allows a natural interpolation to be performed in a moving image including a moving object.
In performing the motion compensation processing, a method of detecting the motion of an object on a block-to-block basis or a pixel-to-pixel basis is widely used, but the method may cause a possibility that the motion detection fails in some blocks or pixels. If the object whose motion has failed to be detected is a high-frequency component, e.g., a character telop, a defect easily occurs in an image with a part at which the detection has failed. For example, since an object including a high-frequency component has a clear boundary with the background, blurs occur at the part at which the detection has failed. On the other hand, since an object including a low-frequency component has a blurred boundary, blurs are not liable to occur if the motion detection fails.
To suppress the defect involving the failure of the motion detection, the following image processing apparatus is provided. The image processing apparatus detects an area including a high-frequency component with motion to be an area for character telop and changes an interpolation method for such an area (see, for example, Japanese Patent Application Laid-open No. 2009-296284). The image processing apparatus detects motion of the entire area in the area of the character telop and detects motion on a block-to-block basis or a pixel-to-pixel basis in the other areas. Subsequently, along the direction of the detected motion, the entire area of the character telop in the original frame is displaced, and in areas other than the character telop, the original frame is displaced for each block or pixel, to generate an interpolated frame. The entire area of the character telop is displaced, so that no blurs occur in the area.